1995A&A...302L..17B

The yield of e- e+ and e- e- bremsstrahlung in the hard X-ray and γ-ray regime from leptonic jets in active galactic nuclei is calculated. We argue that in the case of ultrarelativistic jets where the intrinsic particle spectra have lower cutoffs ~>5 the contribution of e- e+ and e- e- bremsstrahlung overwhelms the yield of pair annihilation radiation which poses severe constraints on models trying to explain spectral bumps at MeV energies observed in the γ-ray spectra of many AGNs by a broadened, blue shifted annihilation line from an ultrarelativistic pair plasma. It is demonstrated that bremsstrahlung emission from a power-law distribution of relativistic particles could as well be responsible for spectral breaks Δα≥0.5 at MeV energies with the instantaneous photon spectra having a flat shape (α∼1.1 in photon number spectrum) at photon energies well below the break.